1. Field of Invention
The present invention relates to an electrophoretic display, and more particular, to a driving technology of the electrophoretic display.
2. Description of Related Art
In an electrophoretic display, charged particles are used to reflect an external light source to display a frame. The electrophoretic display has characteristics of being light, thin, flexible, so that the electrophoretic display is popular with people.
A source driver and a gate driver of the electrophoretic display are coupled to a plurality of pixel units. The pixel units are coupled to a pixel electrode and a common electrode. Generally specking, driving methods of the electrophoretic display include an alternating current (AC) driving method and a direct current driving method. First, the alternating current (AC) driving method of the electrophoretic display is described below.
FIG. 1 is a conventional waveform diagram showed voltages at a common electrode and a pixel electrode under an AC driving method. Referring to the FIG. 1, when a period is changed from a frame period F1 (for example writing a white frame) to a frame period F2 (for example writing a black frame), a voltage of a pixel electrode is changed from a positive voltage Vpos (for example, the positive voltage Vpos is 15V) to a negative voltage Vneg (for example, the negative voltage Vneg is −15V).
It should be noted, in the frame period F1, a capacitor having a voltage difference Vneg−Vpos (for example, the voltage difference is 15V) is existed between the common electrode and the pixel electrode. When period is change from the frame period F1 to the frame period F2, the voltage of the common electrode may be influenced by the voltage variation of the pixel electrode and the capacitor and then changed from the voltage Vneg (−15V) to the voltage Vneg+(Vneg−Vpos) (−15V−30V=−45V) in a moment. The event that the voltage of the common electrode is changed to −45V may easily damage a pixel transistor, the source driver and the gate driver.
FIG. 2 is a conventional waveform diagram showed a voltage outputted by a gate driver under an AC driving method. FIG. 3 is a conventional waveform diagram showed a voltage outputted by a source driver under an AC driving method. The FIG. 2 and the FIG. 3 show that when the voltage of the common electrode is changed to −45V in a moment, an output voltage of the gate driver and the source driver are influenced (show as dotted circles I1 and I2)
FIG. 4 is a conventional waveform diagram showed voltages at a common electrode and a pixel electrode under a DC driving method. The DC driving method is similar to the AC driving method, the voltage vibration of the pixel electrode and the common electrode also may easily damage elements, and the repeated descriptions are omitted herein.